Lightning protection of wind turbine blades has evolved from the rugged (but passive) and solid Light Protection System (LPS) of the past to a modern lightning protection system that can transmit key parameters in real time.
With the introduction of SmartLPS, an integrated condition monitoring system for lightning protection, and Lightning Key Data System (LKDS), a unique measurement system, Danish wind industry supplier PolyTech brings lightning protection into the age of big data.
Most lightning monitoring systems can detect that a lightning strike above a certain threshold has occurred and, in some cases, measure the peak current but not much else. SmartLPS can identify which part of the blade has been hit and make an assessment regarding damage probability. LKDS records key data such as the exact time, peak current, specific energy and charge transfer of the strike.
Depending on which part of the blade has been struck, lightning strikes on wind turbine blades can cause anything from superficial damage to catastrophic failure. Being able to tell one from the other can provide operators with a substantial financial benefit.
"With SmartLPS and LKDS, turbine operators will be much more informed about the consequences of lightning strikes on their turbines. The right information can make a big difference in wind asset management and maintenance. For example, an operator can simply mark the blade for a surface check during the next scheduled maintenance instead of initiating a full emergency stop and launching an unscheduled on-site inspection," says PolyTech CEO Mads Kirkegaard.
The improved ability to accurately gauge the severity and consequences of lightning strikes is also reflected in the industry standards for lightning protection. In the latest revision of the IEC 61400-24w, the standards recognise that risk assessment and lightning measurement can be used to quantify the exposure and thereby define the maintenance intervals.
The revised standards are considerably harsher in terms of requirements and stricter in terms of compliance, with all the previous 'informative' test sections now becoming 'normative'.
In addition, the specific lightning environment for the blade must be defined and documented by the wind turbine blade zoning, making the LPS systems pioneered by PolyTech the new standard.
The core of the SmartLPS system is a distributed array of smart sensors integrated into the lLPS and blade. The sensor data is transmitted in real time to a secure cloud server for analysis and the results published to a secure web portal.
In addition, alarms and warnings can be pushed directly to the monitoring app running on a smartphone or tablet device for instant alerting. This provides turbine operators with previously unseen tools for accurate assessment on potential damage to the blade and they can make informed decisions on the operational planning.
"With this system, we're taking the first step towards more intelligent monitoring of the blades. Lightning is the obvious place to start, but these sensors can act as a system infrastructure for a variety of additional sensors used to measure vibrations, G-force, shock, temperature and more. Condition monitoring of the blade in general will be taken to a whole new level, which provides greater knowledge and lower costs to the asset owner," says Kirkegaard.